Question

Assertion: A basic solution has more hydrogen ions than an acidic solution
Reason: $pH$ is defined as $- \log [{H^ + }]$
A: Both Assertion and Reason are true and Reason is the correct explanation of Assertion.
B: Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
C: Assertion is true but Reason is false.
D: Assertion is false but Reason is true.
E: Both Assertion and Reason are false.

Answer 1

One can solve the question by knowing the concept of $pH$ . The $pH$ of a solution is indirectly proportional to the concentration of ${H^ + }$ ions in the solution. That is, $pH = - \log [{H^ + }]$. So bases have high $pH$ values and acids have low $pH$ .If you know the $pH$ values of given solutions, you will be able to solve the problem.
Formula used:
$pH = - \log [{H^ + }]$
Where ,
$pH$ = The unit of strength of a solution (acidic ,basic or neutral )
$- \log [H]$ = The negation (negative value) of log of molar concentration (concentration of hydrogen ions present in the solution )

Complete step by step answer:
Let us take a solution. It should be of any one from the three types- acidic, basic or neutral basically, but now you don’t know it. The strength of a solution is confirmed on the test for $pH$ . The $pH$ scale has 14 units. If the $pH$ is less than 7, it means that the given solution is acidic and if the $pH$ is greater than 7, it means that it is basic. If the $pH$ of the solution is exactly or approximately equal to 7, then it is neutral. So first check for the given parameters in the question.
There are different kinds of questions that can be asked. They can ask questions by mentioning their actual formula (like $HCl$ or $NaOH$ ) or they will just refer to them as acidic or basic solutions by giving their $pH$ values. The formula $pH = - \log [{H^ + }]$ simply means that the concentration of ${H^ + }$ ions is indirectly proportional to the $pH$ value of the given solution. So if the $pH$ is higher than 7, then the solution is basic. Or if the solution’s $pH$ is less than 7, then it is said to be acidic.
Hence, from the resources, we can say that since the $pH$ of acids is low, it has more ${H^ + }$ ions and more molar concentration. And since the $pH$ of bases are high, they have less ${H^ + }$ ions, which proves the Assertion statement as a wrong one. Since we have found from the $pH$ formula, the Reason is proved correct. From all the steps, we can finally conclude that the Assertion is wrong but the Reason is true.
The answer is Option D- Assertion is false but Reason is true.

Note: You can easily find the solution of these kinds of questions by noting the anion side of the given molecules, if they have not mentioned whether the solutions are acids or bases. In inorganic chemistry, the most commonly used examples for acids are $HCl,HBr,HF,{H_2}S{O_4}$ and $HN{O_3}$ and the most commonly used examples for bases are $NaOH,Ca{(OH)_2},Mg{(OH)_2}$. The bases mostly have ${(OH)^ - }$ ions by their side and the acids have ${H^ + }$ ions by their side.